The lymphatic system includes lymph vessels, lymph nodes, and lymphoid tissues. Lymphatic fluid, or lymph, is collected from the interstitial spaces and is composed of fluids, organic and inorganic materials, and proteins too large for the venous system. In contrast to the closed-loop blood circulatory system, the lymphatic system works generally on a one-way flow principal. The lymph is first collected at the lymph capillaries that, in turn, drain into larger vessels. The movement of the collected lymph is generally from the more distal portions of the body inwardly toward the various lymph nodes and lymphoid tissues. The motive force for the lymph flow is generally associated with contractions of the adjacent muscles and walls of the larger vessels. Foreign matter and bacteria are filtered at various lymph nodes, after which the fluid enters into the venous system, primarily through the thoracic duct. Approximately one to two liters of lymph fluid drain through this duct every day in a healthy individual.
Edema is defined as the accumulation of excess fluid in a body fluid compartment, which is generally apparent as swelling of the affected area. This fluid accumulation can occur in the cells (cellular edema), in intercellular spaces within tissues (interstitial edema), or in potential spaces or cavities within the body. Edema can be caused by a variety of factors, including conditions that affect osmotic pressure, such as hypotonic fluid overload, which allows the movement of water into the intracellular space, or hypoproteinemia, which decreases the concentration of proteins and permits the passage of fluid out of the blood vessels into the tissue spaces. Edema also commonly results from surgery, injury, and other trauma or stress to the body. Vigorous exercise, for example, engaging in competitive sports, can produce stressors in the body, and particularly, in the joints, which result in edema or localized swelling.
Other causes of edema include poor lymphatic drainage (lymphedema); conditions that cause increased capillary pressure, such as excessive retention of salt and water; heart failure; and conditions that increase capillary permeability, such as inflammation. The swelling associated with edema can, in turn, cause pain and impede wound healing. If left untreated, fibrosis (a hardening of the tissue) may further complicate the drainage process.
Causes of lymphedema include aplasia (lack of development) or hypoplasia (underdevelopment) of the lymphatic system; inflammatory diseases, such as bacterial infections; malignancies, where the lymphatics or lymph nodes can be blocked by tumor cells; surgical removal of various lymph nodes; radiation therapy; local trauma to a limb; and blockage of lymphatics by various parasites. Various system diseases can cause lymphedema, including myxedema, renal disease (such as nephrosis or nephritis), and collagen diseases.
The lymphatic system is a primary system in the body for removal of the excess fluids that produce the edema or swelling. A healthy lymphatic system is therefore necessary for preventing and reducing edema. As noted above, the body's muscle systems motivate or assist in the motivation of lymph through the body toward the lymph nodes. It is known that externally applied compressive forces—for example, as produced with a compressive wrap or bandage—can also assist the lymphatic system in reducing and/or preventing edema. Such compressive therapies are often combined with the local application of ice or other cooling systems, which have also been found to prevent or reduce swelling. Alternatively, in some situations, heating of the affected area may be beneficial to the treatment of edema.
Treatment modalities known in the art include compression sleeves or stockings, pneumatic compression devices, and manual lymph drainage apparatus. U.S. Pat. No. 5,904,145; No. 5,906,206; No. 5,916,183; No. 5,918,602; No. 6,196,231; No. 6,254,554; and No. 6,338,723 disclose various designs for compressive sleeves and wraps for the treatment of lymphedema. The devices generally include a plurality of straps used to tighten the sleeve about the limb of the patient. In U.S. Pat. No. 5,904,145 and No. 6,196,231 (issued to Reid), a partially air-inflated pneumatic bladder is used to adjust the pressure applied by the straps. One of the straps is released and the partially inflated air bladder is inserted underneath the released strap adjacent to the patient's limb. The released strap is then closed and tightened to cause a predetermined increase of pressure to be achieved within the bladder. The strap is then released, the bladder is removed, and the strap is tightened to the same position that existed prior to the bladder being removed. These steps are then sequentially repeated with the remaining straps. In U.S. Pat. No. 6,338,723 (issued to Carpenter et. al.), indicia are used to adjust the compression applied by the straps. The stretch of the elastic material causes increased separation of the indicia. A system measures the separation of the indicia and converts it to compression, based upon the circumference of the body part. These systems are cumbersome to apply. A further disadvantage is the application of a static pressure to the limb.
U.S. Pat. No. 5,025,781 and No. 6,315,745 disclose air inflatable/deflatable compression devices. In U.S. Pat. No. 5,025,781 (issued to Ferrari), the compression device is used with a source of cyclical fluid pressure to provide alternating inflation and deflation cycles. The garment disclosed in U.S. Pat. No. 6,315,745 is formed through the patterned sealing of the layers of the garment at select locations to form air pockets that can selectively apply points of pressure to the affected area. In U.S. Pat. No. 5,976,099 (issued to Kellogg), there is disclosed a static reaction system containing a multiplicity of particles that is pressed against the affected area.